allow namespaces to be subdirectories

Unfortunately, gevent-socketio doesn't support that socket.io clients to have their namespaces as a sub-directory. Such as;

    var socket = io.connect('/search', {
      'resource': 'api/socket.io'
    });

will not be treated as a resource on the server-side and you will most likely get a ``KeyError: 'socketio'`` somewhere.

I've made a small tweak within the ``SocketIOHandler`` class, RE_REQUEST_URL and RE_HANDSHAKE_URL regex patterns that it should be fine now.